When Ennis told Jack that he couldn't be with him because he had the girls for the weekend ... why didn't Jack just stick around for a few days? He could have stayed in Riverton or taken a quick trip up to Lightning Flat and stopped on his way back. Why didn't Ennis just say 'Hang on, bud, fer a couple days... I'll make it worth yer wait.'

How would Ennis have reacted if Jack had arrived on Monday, after the girls were gone? He was out in the middle of nowhere all alone--- no excuses! Would the driver of the white truck (or any of the 10 people Jack spoke to in Riverton!) think anything other than Ennis had a fishing buddy visiting? They wouldn't need to know about all the hot man-love taking place in that desolated old farmhouse

I guess Jack was hurt just enough being rebuffed by Ennis that Mexico seemed like the only available salve for his bruised ego.